Vote for your favorite mineral in #MinCup26! - Sphalerite vs. Anorthite Both zinc ore Sphalerite and calcium plagioclase feldspar Anorthite have perfect cleavage that will split cleanly if you hit them with a hammer, but only one can claim a larger split of your votes!
Masses several cm across found in the aplitic zone of the pegmatite. Wet chemical analysis showed it is all bismutite with no remnants of the original mineral, which did not have the elongated crystal habit typical of bismuthinite. X-ray analyses of similar specimens from the area proved to be all bismutite despite the color variation.
Hewitt Gem Quarry, Haddam, Middlesex County, Connecticut, USA